The magnetic dc susceptibility of several amorphous films of Mn-based Heusler alloys exhibits a cusp, characteristic of spin-glass freezing. The cusp temperatures are an order of magnitude smaller than the Curie temperatures of their ferromagnetic crystalline counterparts. The occurrence of the spin-glass state is interpreted in terms of competition between long-range indirect ferromagnetic exchange and direct antiferromagnetic overlap.

• Received 11 March 1982

DOI:https://doi.org/10.1103/PhysRevB.27.562